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Two of the four drain valves tend to leak at times. They're fairly new, so I'm suspecting a burr or other "slight" manufacturing defect. I've turned the orfice and pumped it up and down in hopes of getting it to seat properly, but so far that hasn't entirely cured the problem. However, it doesn't seem as bad as it once was--in fact, one of them seems to have stopped leaking and one has improved. Maybe more turning and pumping up and down or replace?
Oh, yes. The leak is VERY slight; most of the time the fuel evaporates rather than drips.
I had that same problem from the passenger side tank. Seemed to be more of an ooze than a leak. I can see the streak on the bottom of the wing which is how I figured out something was going on. Seems worse when it was cold, but it stopped after about a week. At the time I figured a piece of crud got in there and was preventing the valve from seating properly or the o-ring itself got damaged somehow I jammed it in and out numerous times and added a dab of lithium grease to the shaft and the smidge of lube seemed to do the trick. If it starts up again, I'll change out the o-ring. Not hard to do, but you do have to drain the tank... or have quick hands and not mind getting soaked with gas! :D
mine have always leaked on most all of my planes. Comes and goes. You might try putting a little air thru it from the bottom to blow whatever is in it out. Don't forget to open the cap first, and don't put much in it and split the tank.
After doing what you guys have already done I usually just let it leak and it will usually stop.
Maybe I'm being a bit old-maidish about this, so your comments are somewhat reassuring. That is, I hope that time will cure. I've never encountered this in the other planes I've flown--mostly old ones. I'm gonna keep a watch on it and hope they seat with time/use.
Thanks to all.
the normal parts are cad plated steel and it got to be the way to carry a cleaned up spare and swap it out whenever they leaked. sometimes it was particles on the O ring and sometimes the shaft would get rusty enough to stop free movement.
Best thing I did was buy the SS version or you could get the all brass made ones. been perfect since.
part no. CAV-110-SS
I just replaced the oring in one that has been leaking for a while. couldn't find anything but the hardware store faucet type black rubber. dunno how it'll like ethanol and avgas. wouldn't be surprised to see it start leaking early on. we'll see...
Thanks to everybody for all the helpful tips.